To determine whether the free availability of antimicrobial agents leads to misuse through self-medication, a house-to-house semi-structured interview was held in three different socio-economic areas of Karachi, Pakistan.

Of the 2348 households visited, 1342 (57%) participated ; this included 9209 individuals.

Three hundred and twenty-two (3.5%) had used one or more antimicrobial In the previous 4 weeks, equivalent to 43 agents per 1000 persons per month.

The most frequently used agents were amoxyclllln (16.7%), co-trimoxazole (15.7%), erythromycin (10.9%), ampicillin/cloxacillin (Amplclox, 9.1%) and metronidazole (4.5%). Of these, 91.4% were prescribed by a physician, 2.3% were advised by a chemist and 6.3% were used as self-medication.

Self-medication increased with socio-economic status.

High levels of resistance were found to ampicillin, co-trimoxazole, chloramphenicol and erythromycin.

If these high resistance levels are related to the high frequency of antimicrobial use, over-the-counter availability cannot be held responsible.

Education of the medical profession seems to be the single most important tool to control misuse of antimicrobial agents.